Real world–based immersive Virtual Reality for research, teaching and communication in volcanology

Abstract

Direct outcrop observation and field data collection are key techniques in research, teaching and outreach activities in volcanic areas. However, very often outcrops are of difficult or inaccessible access, such as in areas with active volcanoes or steep cliffs. Classical remote-sensing surveys by satellites or airplanes are expensive, rarely reach sufficient resolution to allow high quality 3D visualisation of volcanic features, and do not facilitate mapping of vertical cliffs. We describe a novel approach that uses the immersive Virtual Reality (VR) based on real world 3D Digital Outcrop Models (DOMs) from images surveyed by unmanned aerial vehicles (UAV). 3D DOMs are built up using the Structure from Motion (SfM) photogrammetry technique, and a Virtual Reality scene is created using game engine technologies. Immersive real-time exploration of the environment is possible through a head mounted display, e.g. Oculus Rift. Tools embedded in the VR environment allow the user to map polygons, lines, point features, measure orientation, dip, inclination, azimuth, area, thickness and even take virtual photographs. Using three examples of volcanic areas with different geological features, we demonstrate the potential of our approach to allow users to be able to virtually map and measure remotely, and to collect data for research and teaching. Our approach is of paramount importance also for outreach, as it allows non-specialist audiences (e.g. common citizens) to experience and appreciate highly complex volcanic features through customised, hands-on immersive VR tools. Response to Reviewers: I have corrected the paper and figures as suggested by the Editor Taddeucci. Author Comments: As suggested by the Editor Taddeucci, I added three videos related to the paper as Supplementary material, and a pdf containing the video captions (a very brief description).

Mapping and evaluating kinematics and the stress and strain field at active faults and fissures: a comparison between field and drone data at the NE rift, Mt Etna (Italy)

“…In the present work, we applied the structure-from-motion (SfM) photogrammetry techniques, through drone surveys, to build up the high-resolution digital surface model (DSM) and orthomosaic for the target area. We followed the overall workflow that has been successfully tested in volcanic terrains and in challenging logistic conditions (Bonali et al, 2019a(Bonali et al, , 2020. Such a workflow has been designed to work with commercial quadcopters over large areas in volcanic terrain; that is exactly the situation we tackled in the present work where we used the DJI Phantom 4 PRO.…”

“…Flight height has been set up to 80-95 m above the ground, reaching the excellent pixel size of 2-3 cm for the resulting orthomosaic. We set the flight path considering the wind speed and direction and chose an overlap ratio of 85 % and 80 %, along the flight path and in a lateral direction, respectively (Gerloni et al, 2018;Antoniou et al, 2019;Bonali et al, 2019aBonali et al, , 2020Fallati et al, 2020). The constant speed velocity was set up by the app considering all the above settings, and pictures have been captured using equal time interval modality.…”

“…In the last few years, the abovementioned difficulties have been overcome by the use of structure-from-motion (SfM) photogrammetry applied to images collected by unmanned aerial vehicles (UAVs or drones) in active volcanotectonics studies (Bonali et al, 2019a(Bonali et al, , 2020Trippanera et al, 2019;Weismüller et al, 2019) and to assess volcanic hazard (Müller et al, 2017;Darmawan et al, 2018;De Beni et al, 2019). Therefore, in this work we use this technique, which allows us to reconstruct very detailed orthomosaics and digital surface models (DSMs) of the surveyed areas.…”

“…Therefore, in this work we use this technique, which allows us to reconstruct very detailed orthomosaics and digital surface models (DSMs) of the surveyed areas. The resulting images, which can attain a resolution as precise as 1 cm, allow us to collect several pieces of high-resolution structural data also in 3D and take direct measurements of structures and morphostructures, like dilation values along faults and fractures, even using immersive virtual reality tools (Tibaldi et al, 2020).…”

Geoheritage and Resilience of Dallol and the Northern Danakil Depression in Ethiopia

“…Vertically dipping, kilometre-long salt dikes are also observable in the W-SW segment of Dallol, forming a series of ridges and depressions, and include rare altered basalts (Holwerda and Hutchinson 1968). These dykes have been partially mapped by Tibaldi et al (2020) using drone images in Virtual Reality, and show several generations of intrusions. West of the Dallol salt canyons, there is a second dome structure called Round Mountain and to the east of Dallol is Horseshoe Mountain (predominantly made up of reddish halite), but these features have not yet been studied in detail (Holwerda and Hutchinson 1968).…”